The invention relates to a compensation reservoir for a hydraulic operating system, in particular a hydraulic brake system or a clutch system, comprising a housing in the interior of which a storage chamber which is provided for storing hydraulic medium is bounded by a separating element which changes its shape in accordance with a volume of the storage chamber.
Compensation reservoirs of this kind are known from the prior art.
However, the problem of being able to identify the magnitude of the volume of the storage chamber in as simple a manner as possible is encountered in the case of said compensation reservoirs.
In the case of a compensation reservoir of the kind described in the introductory part, this object is achieved, according to the invention, in that the housing engages over the separating element in all of its shapes, which correspond to possible volumes of the storage chamber, in a protective manner, in that a filling level-indicating region of the separating element changes its position in the housing when the volume which is taken up by the hydraulic medium which is stored in the storage chamber changes, and this position in each case represents a filling level-indicating position, and in that the filling level-indicating position which is situated within the housing is visible from outside the housing through a viewing region of the housing.